The present disclosure relates to a high-frequency front end circuit including a receiver circuit and a transmitter circuit, and also relates to a communication device including the high-frequency front end circuit.
Communication equipment such as a cellular phone includes a high-frequency front end circuit including a transmitter circuit, which outputs a transmit signal, and a receiver circuit, which receives a receive signal. The receiver circuit of the high-frequency front end circuit includes, for example, a receive filter and a low noise amplifier (LNA) (see Japanese Unexamined Patent Application Publication No. 2013-247605).
When this type of high-frequency front end circuit receives/transmits signals simultaneously, a transmit signal which is output from the transmitter circuit is transmitted not only to an antenna element but also to the receiver circuit. The transmit signal leaks through the receive filter and is received by the LNA. In contrast, in the high-frequency front end circuit described in Japanese Unexamined Patent Application Publication No. 2013-247605, a notch filter is disposed between the receive filter and the LNA, causing the leakage component of the transmit signal to be reduced.
The high-frequency front end circuit described in Japanese Unexamined Patent Application Publication No. 2013-247605 has a problem in that the notch filter attenuates not only the leakage component of a transmit signal but also a receive signal having passed through the receive filter, resulting in reduction in the receiver sensitivity.